Azulene‐Indole Fused Polycyclic Heteroaromatics
Chao Duan, Jianwei Zhang, Shali Cai, Junjun Xiang, Xiaodi Yang, Xike Gao
Abstract
Abstract Linear polycyclic systems are promising candidates in the area of organic electronics. Herein, we present the syntheses of three azulene‐indole (AzIn) fused polycyclic heteroaromatics (PHAs), AzIn ‐ 1 , AzIn ‐ 2 and DGAzIn , which have nitrogens and nonhexagonal rings simultaneously. The chemical structures, optical and electrochemical properties of three AzIn‐based PHAs have been investigated, as well as their protonation behaviors with trifluoroacetic acid (TFA). All three AzIn‐based PHAs exhibit narrow optical band gaps with moderate to good air stability, anti ‐Kasha emission and reversible stimuli‐responsiveness. Furthermore, these straightforward and simple synthetic routes would provide a new entry for constructing novel azulene‐embedded π‐conjugates, especially for the seven‐membered ring of azulene unit, wherein the regioselective transformation is not well developed.